[guar.an.tee] n [prob. alter. of [1]guaranty] (1710) 1: guarantor
2: guaranty 1
3: an assurance for the fulfillment of a condition: as a: an agreement by which one person undertakes to secure another in the possession or enjoyment of something b: an assurance of the quality of or of the length of use to be expected from a product offered for sale often with a promise of reimbursement
4: guaranty
4.
[2]guarantee vt -teed ; -tee.ing (1791) 1: to undertake to answer for the debt, default, or miscarriage of
2: to engage for the existence, permanence, or nature of: undertake to do or secure "~ the winning of three tricks"
3: to give security to
4: to assert confidently